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Thread: prop sizes

  1. #1

    prop sizes

    I am pretty new to the pwc world and i"m trying to understand more about them. I was wondering on certain watercraft, the bigger the motor (HP) is there a different type or designed prop system compared to a smaller motorized ski? I know you have to transfer all that HP to the prop. Kind of like with cars, bigger motor transfer the HP to wider tires hence better performance. Is there some coralation?

  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    More HP usually runs bigger numbered impellers. For example... 650 uses a 12/17, 750 uses 13/18, a 1200 may use a 17/24 and so on. BUT, there are also reasons to run a smaller impeller with big HP, like on the PRO 785. The smaller impeller allows the engine to turn more RPM where an exhaust system is tuned to be most efficent.A 12/17 on a Pro may allow it to turn close to 8000 RPM. A 13/18 may allow it to turn 7600 RPM. But the pipes are most efficient at 7800-7900 RPM and that's what makes the most power, in the sweet spot.

  3. #3
    What do the numbers stand for in the prop description? Always wondered that.

  4. #4
    Prop pitches will fluctuate amongst the different types of props. One Prop, for example, with a pitch of XX might rpm the same as a different type prop with a totally different pitch. Don't go by what the pitch says. You want to get a prop that will operate in your either stock exhaust pipe, or Pipes(if more than one) rpm range as well as what modifications you have. Confusing. Basically, tell people here what you got, and what you're looking for(top speed, accelleration, etc.) and someone will chime in. GroupK explains it in his website if you look for it. WWW.GROUPK.COM

  5. #5
    Impeller pitches - All the impeller manufacturers have adopted their own pitch measurement systems. Unfortunately, no two of these measuring systems seem to be the same. This situation means that the pitch numbers offered by each maker are useless information to potential prop buyers (a situation that the prop builders ought to remedy). Just the same, engine builders must come up with some sort of system by which "they" can compare different pitches from different manufactures. At Group K, we turn a blind eye to the pitch numbers, and instead base our comparisons on how each prop "loads down" a particular engine format at low rpms and high rpms. It may not sound very precise (it's not), but it's more meaningful than anything being offered by the prop builders. Our system uses the stock prop as a "0" base, and goes plus for higher pitches..minus for lower pitches. Note : as more props are available and tested, we will include them on our chart.
    Solas X2 / +3 Solas X1 / +.2
    Stock XP /0 Stock GSX / -.1 Nu Jet / -.5 Skat Trak swirl 17/22 / - 1.5 Solas Xo / -2 Solas X / -4

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